Customer satisfaction is measured by how satisfied customers feel about their experiences with a brand or product. Customer loyalty can be sustained through customers who consistently pay on time, spend above average amounts, refer others, purchase additional items, and have purchased for a long time. There are different types of customers like endorsers who refer others, buyers who continue purchasing but don't endorse, and various levels of satisfied, dissatisified, grumbling, and complaining customers. Customer service can be good when expectations are met, bad when expectations aren't met, and excellent when expectations are exceeded. Getting feedback is important for improving products, services, and the customer experience.